The growth of the electronics industry from discrete components, such as individually packaged transistors and diodes, through large-scale integrated circuits is a well-recognized, remarkable development. The next step, for some companies, is to extend the technology to what is known as wafer scale integration. Under this concept, circuitry is formed on a full-size silicon wafer, typically 3-4 inches in diameter, instead of on individual silicon wafer chips, which measure only about 1/4 inch on a side. A single wafer scale integrated circuit is expected to replace on the order of 100 large-scale integrated circuits.
One reason for developing wafer scale integration technology is that the number of external hardwire connections is substantially reduced since the hardwire connections which would otherwise be needed between chips are eliminated. Wafer scale integration is expected to reduce the cost of a complex system, increase its reliability and increase its speed.
Because of the great number and density of components in a wafer scale integrated circuit, a substantial amount of heat, for example 1,000 watts, is generated during use. This heat must be properly dissipated to keep the integrated circuit from being destroyed. The heat must be removed both during the normal operation of the integrated circuit and also during its testing.